A couple of teenagers break into a secret government science lab and steal a frozen corpse for a high school prank and accidently awaken the corpes which turns out to be a CHUD, ironically named Bud, who goes on a killing spree and making his victims also canabalistic CHUD's and its up to the teens to stop him.

Movie Tagline:
Their first mistake was stealing a corpse... Their second was waking him up.